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Topic: Group size 100 vs. 300 (Read 702 times) previous topic - next topic

Re: Group size 100 vs. 300

Reply #15
Good job fuj. Way better than I could do shooting like that.
Grant

Re: Group size 100 vs. 300

Reply #16
Sorry gentlemen. I have been away from the computer for awhile. Thanks for all of the input.  To answer 6.5 savageguy's question I was thinking in terms of MOA.  I can't understand how a 1 inch group at a 100 yards can translate to a less than 3 inch group at 300 yards.
Live with honor and ride with courage. Be friendly to all those you meet.  But always carry a knife in your boot and a gun on your hip 'cuz there are those that don't think the same as this.

Re: Group size 100 vs. 300

Reply #17
Sorry gentlemen. I have been away from the computer for awhile. Thanks for all of the input.  To answer 6.5 savageguy's question I was thinking in terms of MOA.  I can't understand how a 1 inch group at a 100 yards can translate to a less than 3 inch group at 300 yards.

I feel the same way, all other things being equal, which they may not be. Time-in-flight alone may allow other factors which may not affect a bullet at 100 yards to have a material effect later in the trajectory. As much as it seems to me those forces would serve to negatively affect group size, who knows, sometimes the sum of those vectors may positively affect group size.
Chris

Re: Group size 100 vs. 300

Reply #18
litz’s newest book has a chapter on this phenomenon (myth).  he concludes that excluding non-repeatable variation (of which rarodin speaks above) a smaller moa group at distance is not possible.

have there been cases where it happens? absolutely, but it’s by chance, or luck if you will.

can anyone provide a gun where it happens all the time, often, or even somewhat frequently? he’d love to study that gun :)

Re: Group size 100 vs. 300

Reply #19
  I can't understand how a 1 inch group at a 100 yards can translate to a less than 3 inch group at 300 yards.

I look at it this way......Shooting a One MOA group at 100, those bullets
are now still traveling to reach 300. In all probability, if nothing effects the
flight  path, you'll get a 3" group.....Now change the conditions. Take that
same load you just shot at a one MOA group at 100,  and head over to the
300 yard range, set up for that range, and shoot it.
Keeping my bad Kharma intact since 1952

Re: Group size 100 vs. 300

Reply #20
litz’s newest book has a chapter on this phenomenon (myth).  he concludes that excluding non-repeatable variation (of which rarodin speaks above) a smaller moa group at distance is not possible.

have there been cases where it happens? absolutely, but it’s by chance, or luck if you will.

can anyone provide a gun where it happens all the time, often, or even somewhat frequently? he’d love to study that gun :)

One part of the equation is the person yanking the trigger. I regularly shoot
smaller MOA as the distance increases. Tell Mr. Litz to study the person. If
a rifle and ammo is consistent, the variable is the shooter. Some shooters can
focus, and tighten up their mechanics better, as the distance increases.
Physical law is physical law but it's still the shooter at that moment in time,
that breaks the shot.....I don't need a flame suit.  :D
Keeping my bad Kharma intact since 1952

Re: Group size 100 vs. 300

Reply #21
One part of the equation is the person yanking the trigger. I regularly shoot
smaller MOA as the distance increases. Tell Mr. Litz to study the person. If
a rifle and ammo is consistent, the variable is the shooter. Some shooters can
focus, and tighten up their mechanics better, as the distance increases.
Physical law is physical law but it's still the shooter at that moment in time,
that breaks the shot.....I don't need a flame suit.  :D

Anytime I can just hold my MOA at distance I feel I’ve done a good job reading and adjusting to the conditions. I shoot in the mountains of Colorado and the wind is very devious.

 

Re: Group size 100 vs. 300

Reply #22
can anyone provide a gun where it happens all the time, often, or even somewhat frequently? he’d love to study that gun :)

I'll ask my 6mm Norma BR friends to elaborate on how repeatable their claim is that their rifles shoot smaller MOA past 200 yds than inside 200 yds.
Chris

Re: Group size 100 vs. 300

Reply #23
Is it better concentration at distance? The dot appears smaller at distance so you have a smaller aiming point?
RPR 6.5 Creedmoor
Bergara 6 Creedmoor

Re: Group size 100 vs. 300

Reply #24
One part of the equation is the person yanking the trigger. I regularly shoot
smaller MOA as the distance increases. Tell Mr. Litz to study the person. If
a rifle and ammo is consistent, the variable is the shooter. Some shooters can
focus, and tighten up their mechanics better, as the distance increases.
Physical law is physical law but it's still the shooter at that moment in time,
that breaks the shot.....I don't need a flame suit.  :D

pretty sure the shooter falls into the class of non-repeatable variation :)

Re: Group size 100 vs. 300

Reply #25
I'll try to explain, using an analogy, how it is possible to have a smaller group size at distance than you would get at a closer range.  First, we must assume that there is 'whip' in the barrel as the propellant ignites and the bullet races toward the muzzle.  Let us assume, for simplicity, that the oscillation is purely in a vertical plane...up and down solely.  If the barrel is in transit from its lowest position toward its highest position when all bullets in question are exiting the muzzle we can agree that a faster bullet will reach the muzzle when it is at a lower angle of trajectory than a slower bullet.  This means that a slower bullet will be launched at a higher trajectory than a faster bullet.  I assume we all agree at this point....if not I wear Nomex undergarments while at the keyboard ;) .  Now.... consider a battleship off the Normandy coast firing 16" rounds at a German pillbox on the coast 5 miles out and they have two loads...a high trajectory load that uses one bag less blackpowder and a lower trajectory load that uses one more bag of blackpodwer and the gun has to use a higher elevation to zero in on the pillbox with the lower velocity charge than the faster charge...but they both impact on the same spot onshore.  Can we agree that there is divergence of the rounds from the exit of the gun's muzzle but then convergence on the target and that at 1 mile the 'group size', if multiple high/low velo/trajectory loads were fired, would be greater at 1 mile than at the target?  Theory again...but does happen in practice.  A crude analogy perhaps.

EDIT-  this situation would only occur in a rifle if the velocities were varying but tuned to that particular distance...the convergence point.  However, if a rifle's loads had an ES of '0' and it shot 1 MOA at 100 yds then the distance grouping would be no better than 1 MOA without some outside force randomly forcing the bullets toward convergence.  That is why sometimes I, and many others, find a great load at a particular long distance that has an ES of 25-30 and the low ES loads in the test shot like crap.  It also indicates a not so good tune on the rifle.  If that is all I can get I will roll with it but I much prefer is my most precise load also has a very low ES/SD; this means if it groups well at 100, I can expect excellent grouping at 600 and 1000yds.  

Re: Group size 100 vs. 300

Reply #26
pretty sure the shooter falls into the class of non-repeatable variation :)

True...but that variation can be extremely small in the case of a well tuned F-open front rest/rear bag and properly tracking stock....even smaller in a bench rest set-up and even less so with a benchrest rail gun.  However, that is a small minority of rifleshooters world wide.

Re: Group size 100 vs. 300

Reply #27
"FIRE MISSION".....  Dang !! Feel like I'm back in Arty school.  :D
Indirect Fire Crewman / 81 Mortar "11 Charlie"/ Gunner First Class.


Keeping my bad Kharma intact since 1952

Re: Group size 100 vs. 300

Reply #28
 ;D
True...but that variation can be extremely small in the case of a well tuned F-open front rest/rear bag and properly tracking stock....even smaller in a bench rest set-up and even less so with a benchrest rail gun.  However, that is a small minority of rifleshooters world wide.

I would agree.  And not unless computers are now used to pull the trigger,
We are part of the gun at every aspect until the pill leaves the barrel.
Keeping my bad Kharma intact since 1952

Re: Group size 100 vs. 300

Reply #29
I believe it to be unlikely you will consistently shoot smaller groups at 300 yd. than at 100 yd. unless you have optics problems. I've come across a number of scopes that had terrible parallax problems up close but were better at a distance closer to 200 yd. Most scopes without parallax adjustments are permanently set to be parallax free at 150 yd. to 200 yd.